This invention relates to document image capture systems and more particularly to digital systems for scanning documents and digitizing the image thereof for subsequent storage, retrieval and manipulation.
Many methods of document image storage are known in the prior art. Early attempts at image storage utilized so-called "hard copy" image storage such as microfiche, microfilm or reduced photocopies. More recently, document images have been obtained utilizing electronic video equipment, and still more recently, utilizing digital electronic video equipment.
Typically, in a digital document image capture system, a moving document is repetitively scanned in one axis and individual sections of the document are assigned a value as either a "black" or "white" section, as a result of a comparison with an arbitrarily assigned reference value. This simplistic approach to rendering a document image into a series of "black" or "white" sections is sufficient for many applications; however, if the system must operate upon multihued documents, such as personal checks, it is possible that the background color of a particular document may exceed the reference value, and therefore may result in the entire image being classified as "black."
Further, an optical sensor is typically utilized to detect the presence of a document prior to the initiation of digitization in such known systems. This additional piece of electronic equipment provides a possible source of error, in that a malfunction of the optical sensor may result in a document passing through the system without being scanned.